Berlin 2015 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 1: Colloids and Complex Liquids I (joint session CPP, BP, DY)

CPP 1.5: Vortrag

Montag, 16. März 2015, 10:30–10:45, C 130

Colloidal Plastic Crystals of Hard Dumbbells under Shear — •Nils Heptner^1,2, Fangfang Chu^1,2, Matthias Ballauff^1,2, and Joachim Dzubiella^1,2 — ¹Helmholtz-Zentrum Berlin, Germany — ²Humboldt-Universität zu Berlin, Germany

We study the structural response of plastic crystals of colloidal dumbbells to an oscillatory shear field using Brownian Dynamics (BD) computer simulations. Under increasing shear strains, a discontinuous transition is found from a twinned-fcc like crystal to a partially oriented highly ordered sliding-layer state via a disordered intermediate state. In this novel partially oriented sliding-layer phase, sheared hard dumbbells exhibit a small but finite collective orientational order. We show that the orientations of only weakly anisotropic particles play a crucial role in non-equilibrium transitions. Our findings from simulations are compared to data obtained by rheo-SANS experiments and reveal the nature of a second rheological yielding event which has not been observed for crystalline suspensions of hard spheres.